[ExI] Extraterrestrial liberty and colonising the universe

Anders Sandberg anders at aleph.se
Sat Jun 22 11:45:31 UTC 2013

On 21/06/2013 15:29, Dennis May wrote:
> Why aren't we a thousand miles deep in grasshoppers?
> A: disease, parasites, predators, cannibalism, resources to 
> survive/replicate.

This applies if you have a system where evolution applies. The standard 
interstellar replicator scenarios tend to use multiple local hops, 
allowing many generations between the start and end point. Plenty of 
chance for evolutionary drift or divergence, although artificial probes 
can be equipped with error correction making any accidental diversity as 
negligible as you want. Stuarts and mine scenario has two generations: 
the end-state will not have had much chance to evolve (and, again, error 
correction can prevent it).

The assumption that given time parasites will evolve is based on the 
image that the system is free to evolve. But non-evolving replicators 
getting there first can also prevent the appearance of evolving 
replicators. If the first seeders didn't want to allow them, they could 
do it. We might *like* the concept of evolving replicators a great deal 
more than those boring non-evolving, but the latter can win against the 
rest if they are programmed to be through.

...however. I have a poster at a conference in two weeks 
<http://star-www.st-and.ac.uk/%7Eap22/setinam2013.html>) where I do a 
further analysis of the stability of this kind of scenario. Basically 
non-evolving probes preventing the spread of evolving parasites (that 
is, other civilisations) must be vigilant and effective in order to be 
an explanation of the Fermi question. I show that even when taking 
anthropics into account our existence is a counter-argument, and in 
addition such systems do not seem to be stable against invasion - the 
only way to be truly certain nobody else can invade is to turn 
everything into your kind of replicator. Hence the "deadly probe 
scenario" is not a likely answer to the Fermi question.

Anders Sandberg,
Future of Humanity Institute
Oxford Martin School
Faculty of Philosophy
Oxford University

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